When the diagnosis of hypoadrenocorticism is made, it is of interest to know whether it is caused by a primary (adrenocortical-dependent) or secondary (pitituary-dependent) lesion. This is done by measuring adrenocorticotropic hormone (ACTH). Canine ACTH is rapidlydegraded in plasma and standard recomends centrifugation in cold centrifugs, stored and shipped frozen. This advanced handling procedure complicates the use of this diagnostic tool in every day practice. In horse medicine the guidelines for sample collection and storage havereecently been changed due to that ACTH have been shown to be more stable than expected. The purpouse of this study is to measure the stability of ACTH in canine plasma to evaluate the possibilities of simplified guidelines for sample collection and storage. This is done by testing how fast the concentration of ACTH in canine plasma is degraded at different storage temperatures and storage times. The result of the study indicates that ACTH is stable enoughfor sample collection and handling in room temperature and shorter storage under chilled conditions.